Drawing-press



C. 8. SMITH AND A. Z ISKA, In.

DRAWING PRESS.

APPLICATION man MAR 22. 1920.

Patented Oct. 26, 1920.

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DRAWING PRESS.

APPLICATION FILED MAR. 22. 1920.

Patented Oct. 26, 1920.

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INVENTORS Cfiarb:.5millz and Ida: 21.4%: J @umu A a. 0.3M)! arr.) 10% Y W HTTORNEYfi UNITED STATES PATENTIOFFICE.

CHARLES S. SMITH AND, ADAM Z-ISKA, JR, OFIIILWAUKEE, WISCONSIN, ASSIGNORS TO A. 0. SMITH CORPORATION, OF MILWAUKEE, WISCONSIN, A. CORPORATION OF NEW YORK.

DRAWING-PRESS.

Specification of Letters Patent.

Application filed larch 22, 1920. Serial N0. 367,641.

To all whom it may concern:

Be it known that we, CHARLns S. SMrrn and ADAM ZISKA, J r., citizens of the United States, and residents of the cit of Milwaukee, county of Milwaukee, and tate of Wisconsin, have iointly invented certain new and useful m rovements in Drawing- Presses, and we 0 declare the following to be a full, clear, and exact description thereof, such as will enable others skilled in art to which the invention pertains to make and use the same, reference being bad to the accompanying drawing for an illustration of one construction in which the invention has been embodied.

The invention relates to presses for drawing sheet metal plates and blanks into shaped articles.

Drawing presses of the type mentioned are usually nipped with a base supportlng a bed upon w ich latter is placed the matrix forming one of the die members of the ress, and with a vertically reciprocable ead which carries the punch or complemental die member, such die members being contoured so as to impart the desired shape to the article formed from the blank. In constructing such presses a longitudinally extending eccentric or crank shaft 1s 10111- naled in bearings at the under side of the crown piece at thetop of the press, and above the longitudinal center line of the reciprocating head, the said. head bemg connected to the eccentric or crank shaft by a series of eccentric links or pitmen, operated by the eccentrics or cranks, with which the shaft referred to is provided.

Straining rods arranged in series at each side of the press, connect the base with the crown thereof, so as to tie together the bed and the crown, and constitute a resistance or means of confinement of the pressure generated by the rotation of the eccentric or crank shaft in operating the punch to per form the drawing operation upon the metal plate or blank.

The straining rods before referred to are arranged in parallel rows at the sides of the press, and in large presses each row is composed of six or more of such rods, to secure the necessary rigidity in the press structure. From the construction descrlbed, it will be seen that the rows of straining rods, one at each side of the press, and connecting the crown of the press with the Lase, receive the the entire tension to which the press is subjectedwhile performing the drawingeiperation. I

the straining rods, and serve to guide the head in its vertical reciprocations. The 0pposing faces of the bed and of the head of the press, upon which the die members are positioned, are separated a good distance to facilitate the insertion and removal of the die members, in order to adapt the press to the performance of a class of work in which considerable variation exists. The separation of the working faces of the die members must be taken up by the motion of the eccentric shaft, and this necesitates the employment of eccentrics or cranks of considerable throw. It has been observed that in moving the head from its elevated position to perform the drawing operation, the eccentrics or cranks, by reason of the diameter of the circular path traversed-by them, and the angle upon which the pressure is applied. cause the head to exert considerable lateral pressure upon the straining rods by which the head is guided.

In drawing articles somewhat irregular in form, the die members cannot be arranged in the press with such exactness that there will be an even distribution of the pressure exerted in the drawing operation, and as a result of this unavoidable condition the resistance ofiered by the metal late or blank between the dies varies from t e line upon which the eccentric links are connected to the head, so that the pressure exerted by the eccentrics is unevenly applied. The result of this action is that the head will follow the path of the least resistance, and will bear unevenly and with great force against some of the straining rods by which it is guided.

In constructing our improved press, we have been actuated by a desire to devise some means whereby a better distribution of the strains could be effected, and in which improved press the objections hereinbefore adverted to as inseparable from the operation of the common type of presses could be overcome, and the head of the press be made to follow its movement to perform the drawing operation, without exerting the lateral pres sure against the straining rods which guide the head, as in the presses of older construction.

After some experimentation, we have constructed a press which is now successfully operating upon the lines which we have been pursuing, and in which the strains created by the operation. of the eccentric actuating mechanism for the head are evenly distributed, and this without re rd to the arrangement in the press of the ie members with. reference to the lines upon which the pressure of the eccentrics is applied.

In our improved press, we journal in parallel relation under the crown of the press a pair of eccentric shafts, which are geared together so as to rotate in synchronism. A series of eccentric links connects each eccentric shaft to the punch carrying head of the press along the lines of the vertical planes of the eccentric shafts. By thisarrangement of a plurality of eccentric shafts geared so as to rotate in exact timing, the head of the press is given a parallel motion during all parts of its movement, and no lateral strain is imposed upon the guides for the said head. a

In the foregoing, we have referred to parallel eccentric shafts as being embodied in the construction. Such reference however is merely figurative, inasmuch as in the actual construction the said eccentric shafts are composed of short, independently journaled sections, arranged in pairs and geared to operate in unison. The gear with which each shaft section is provided is flanked at each side by an eccentric formed upon the projecting ends of each of the eccentric shaft sections. The number of such eccentric shaft sections may be as desired, and motion is transmitted to the pairs of gears and their eccentrics by means of suitable pinions upon a lay shaft extending the length of the press,and driven through appropriate reducing gears from the primary shaft of the press.

The invention has been embodied in a press having capacity for drawing in one operation a flanged channel bar 18 feet long, the particular embodiment of such channel or flanged bar constituting the side bar of an automobile frame, and the press is capable of exerting a pressure of about 3,000 tons upon a metal plate or blank ths of an inch in thickness.

The press has been especially constructed so as to be open at both sides for the feeding of the work. This has necessitated the construction of the bed, the end frames, and the crown in such proportions as to insure the necessary rigidity of the structure when subjected to the enormous strains incident to the production of heavy work. By constructing the press so as to dispense with the usual parallel rows of straining rods at the sides of the press. the time required to feed long blanks, within the limitations imposed by the distance the end frames are separated, is materially reduced, and has enabled us to greatly increase the output of the press. However, the end frames are provided with openings in line with the bed of the press, through which may be fed blanks of such length as cannot be fed from the side and cannot be drawn in a single operation. Flanged bars having a length exceeding that of the openings at the sides of the press, and consequently exceeding the length of the die members, are first positioned for one drawing operation and then positioned for a second like operation, to complete their formation.

By forming the eccentric shafts in sections, and operating them jointly, the torsional strains to which the usual single eccentric shaft is subjected, are practically eliminated.

Referring to'the accompanying drawings,

Figure 1 is a side elevation of our improved press, broken out in parts to show certain structural features, and indicating also for mere purposesof comparison, the relative dimensions of the press, which is now in operation.

Fig. 2 is an enlarged sectional view on the line 22, Fig. 1, looking in the direction of the arrow, and indicating our improved arrangement of synchronously operating eccentrics for imparting a parallel motion to the punch carrying head of the ress.

Fig. is a perspective view of one of the eccentric sha t sections, its eccentric and actuating gear, and showing in dotted lines one of the eccentric links used for connecting the eccentrics with the head.

In the drawings, A indicates the bed of the press, B and B the end frames, and C the crown piece. These frame elements are formed into a unitary structure by tie rods 6, the threaded ends of which receive nuts 5. The nuts at the lower ends of the tie rods are not shown in the drawings, but their arrangement will be understood. These rods must be of such diameter and tensile strength as will enable them to withstand the expansive strains generated in the operation of the press, and thus constitute a rigid structure. The base A and the massive crown' piece C, are likewise formed in such proportions as to enable the necessary rigidity of the frame to be maintained at all times during the operation of the press. The top of the base is formed as a plane surface to constitute the bed a of the press, upon which will be secured the shoe a, in which is placed the matrix member of the dies, as usual, in drawing presses.

The punch carrying head of the press, indicated D, and to the face of which the punch d is attached, is confined at its ends by vertically arranged guides d whereby movement of the said head is restricted to vertical reciprocation in the path defined by the said guides d As shown in Figs. 1 and 2, the under side of the crown C is provided with depending bearings O for the parallel eccentric shafts C formed in sections, there being in the press six of such sections, three in axial alinement at each side of the longitudinal center line of the press. Each eccentric shaft section is provided at each of its ends with an eccentric c, and a gear E at its mid length. The depending bearings C of each set are spaced to receive the gear E between them, and each bearing is divided for the reception of the eccentrics c and their straps c as indicated in Fig. 1, the eccentric shaft sections C being journaled at four points in each set of bearings. The gear E upon the eccentric shaft section is in mesh with the gear upon its companion shaft, so that such shafts and their eccentrics rotate in unison.

A driving shaft F extends the length of the press at one side thereof and is provided with pinions 7, which engage gears 1 upon a sha t f. The shaft f, likewise extending the length of the press, is provided at each end with a pinion f in mesh with gears f upon the ends of the lay shaft f". The said lay shaft f carries pinions f which engage with one of each pair of the gears E, and through the latter transmit'a movement of rotation to the eccentric shaft sections.

In Fig. 20f the drawings, we have indicated by a broken line the longitudinal center of the press. In the eonstructions of drawing presses hereinbefore referred to as constituting presses of the older type, the eccentric shaft and the points of connection of such shaft with the unch carrying head, are bisected by such ongitudinal line. The effect of this arrangement is that the eccentrics upon reaching the point of their extreme lateral movement in performing the drawing operation, act to transmit an an lar pressure through the head upon t d vertical straining rods b means of which the said head is guided. This operation is productive of a large amount of friction between the eccentric head and the vertical guiding rods and inasmuch as the direction of rotation of the eccentrics is constant, a severe strain is exerted always at one side of the press. The powerful pressure thus generated exerts a violent movement of the whole press structure, as a reaction of the thrust of the eccentrics.

The connection of the actuating eccentrics with the punchcarrying head being made at the longitudinal vertical center thereof, in

the older forms of presses, as described, and in the plane indicated b the broken line referred to, the said hea cannot be made to partake of a parallel motion, when the pressure exerted by resistance in the drawing operation is not evenly divided at the longitudinal center line of the press. As a result of the impracticability of evenl f distributing the pressure over the face of t e punch carrying head in the older form of presses, the said head developed a tendency to depart from the line of its movement in the desired parallel plane, and eflect a rocking engagement with the means provided for guiding it in its vertical reciprocations. The result of this condition is that the frictional engagement between the said head and its guides due to the angular thrust of the eccentrics, is largely increased in those operations in which the tendency'of the punch carrying head is to rock in the direction of the angular thrust of the eccentrics.

By mounting an eccentric shaft at each side of the longitudinal center of the press, and connecting such eccentrics to the punch carrying head in the vertical planes in which the eccentric shafts are mounted, the angular thrusts generated in the operation of the eccentrics oppose each other, but at the same time the forces are equalized. The result of this operation is that the unch carrying head is given a parallel motion through its entire reciprocation, and the guides for the said head are relieved from the angular pressure co-existent with the construction of the press of the older type. The head therefore moveswith a greatly lessened frictional engagement with its guiding means.

Another advantage which flows from the arrangement of the devices for. preserving the parallel motion of the punch carrying head, is that the dies may be placed in the press without regard to the longitudinal center line thereof, or even entirely at one side of such line, and the parallel motion of the head will be preserved, without tendency to rock against and increase the frictional engagement with its guiding means. The press is now operated with a set of dies at each side of the longitudinal center line, the dies at one side producing a right hand frame bar for an automobile, and the dies at the other side producing a similar left hand bar at one operation of the press, two gangs of pressmen, one at each side of the press being em loyed. As a matter of fact,

the press is a so operated to produce onetype of side bar, in the absence of the gang of pressmen at the other side, the resistance interposed at one side of the longitudinal center line not affecting the parallel movement of the drawing head.

As a matter of convenience in description, we have referred to the improved press as being provided with two parallel eccentric shafts. However, it will be understood from what has been hereinbefore stated, and in accordance with the showing of the drawings, that such parallel eccentric shafts are not integral shafts, but that each is formed in sections. One reason for adopting this sectional construction is to avoid the very diflicult and expensive operations which would be encountered in the attempt to form with exactness and precision the eccentric shaft with its several eccentrics as an integral structure. Another reason for the improved arrangement is that the sectional shafts with their gears and eccentrics may be lifted tnto place in opened bearings depending from the crown piece of the press with facility, and the necessity for forming journals for the shaft in the end frames is obviated. Again, our improved construction of the eccentric shaft in sections eliminates the torsional strain occurring in an integrally formed eccentric shaft, which in the older forms of presses carry as many as six eccentrics, driven by gears at the ends of the shaft. In forming or using such integral eccentric shaft, the whole must be discarded in the event that a defect occurs in one part of the shaft, but with our sectional construction, any defect which may arise, will affect only the particular section involved, and which may be replaced by another, without incurring the great loss which would be involved in discarding the whole shaft by reason of a defect affecting only one part thereof.

Although the invention hereinbefore disclosed has been embodied ina drawing press, it will be understood that its employment is not to be so limited, but that it is equally applicable to use in blanking presses and other forms of presses.

Having thus described our invention, what we claim and desire to secure by Letters Patent of the United States, is:

1. A metal working press, comprising a base, end frames and a crown united to form a unitary structure, a reciprocating head guided for vertical movement in the structure, eccentric shafts supported by the crown at each side of the longitudinal center line of the head, connections from the eccentric shafts to the said head, and means for rotating the eccentric shafts in synchronism, whereby a parallel motion is imparted to the head.

2. A metal working press comprising a base, end frames and a crown united to form a unitary structure, a reciprocating head guided for vertical movement in the structure, parallel eccentric shafts su ported by the crown andconnections there om to the head at each side of the longitudinal center line of the head, and gears for rotatin the eccentric shafts in synchronism, where y a parallel motion is imparted to the head.

3. A drawing press for shaping articles from sheet metal blanks, such press comprising a base, end frames and a crown united to form a unitary structure, the base supporting one of the die members, a vertically reciprocating head carrying the complemental die member, parallel eccentric shafts supported by the crown and connections therefrom to the head at each side of the longitudinal center line of the head, whereby the thrusts of the eccentrics at each side of the center line are equalized and a parallel motion is imparted to the head.

4. A drawing press for shaping articles from sheet metal blanks, such press comprising a base, end frames and a crown united to form a unitary structure, the base supporting one of the die members, a vertically reciprocating head carrying the complemental die member, parallel eccentric shafts journaled in the structure and connections from the eccentric shaft to the reciprooating head at each side of the longitudinal center line of the head, whereby the thrusts of the eccentrics at each side of the center line are equalized and a parallel motion is imparted to the head. i

5. In a drawing press for shaping articles from sheet metal blanks, a reciprocating head upon which is mounted one of the work shaping members, parallel eccentric shafts and connections therefrom to the head at each side of the longitudinal center line of the head, and gears for rotating the eccentrio shafts in synchronism, whereby thethrusts of the eccentrics at each side of the center line are equalized and a parallel motion is imparted ,to the head.

6. A drawing press for shaping articles from sheet metal blanks, such press comprising a base, end frames and a crown united to constitute a unitary structure, the base supporting the matrix, a vertically reciprocating head carrying the punch, parallel eccentric shafts supported in the structure and connections therefrom to the head at each side of the longitudinal center line of the head, and gears for rotating the eccentric shafts in synchronism, whereby the thrusts of the eccentrics at each side of the center line are equalized and a parallehmotion is imparted to the head.

7. In a drawing press for shaping, articles from metal blanks, a unitary press structure composed of a base, end frames and a crown; a reciprocating drawing head guided for vertical movement in the end frames, parallel eccentric shafts supported in the structure and connected to the drawing head at each side of the longitudinal center line of the head, the said eccentric shafts being formed in separate-sections, intermeshing gears for rotating the shaft sections in synchronism, a lay shaft and pinions thereon for transmitting motion to the shaft sections through .the intermeshing gears, whereby the thrusts of the eccentricsat each side of the center line are equalized and a parallel motion is imparted to the head.

8. In a drawing press for shaping articles from sheet metal plates, a driven lay shaft provided with a series of pinions, a series of alined sectional eccentric shafts provided with gears engaged by the said pinions, a parallel series of alincd sectional eccentric shafts provided with gears intermes'hing with the gears on the first mentioned sectional eccentric shafts, whereby all of the eccentric shaft sections are rotated synchronously, a reciprocating drawing head and connections from the parallel eccentric shafts thereto at each side of the longitudinal center line of the drawing head, whereby the thrusts of the eccentrics at each side of the center line are equalized and a parallel motion is imparted to the head.

9. In a metal Working press, a reciprocating head carrying one of the Work shaping members, parallel eccentric shafts geared to rotate in opposite directions, and means (minecting the eccentric shafts to the licad :d separated points, whereby a parnllcl mo tion is imparted to the latter.

10. In a metal working press a reciprocating head, a plurality of parallcl shafts carrying eccentrics and means for rotating the said shafts in unison, and (lilillli'ilulh between the eccentrics and the head. \\'ll0]l by the pressure of the eccentrics upon the said head is distributed over the latter.

In testimony whereof, we have signed our names at Milwaukee, this 16th day of Ma rcl S. SMITH. ADAM ZISKA, JR. Witnesses:

W. F. lVooIr-mn, V A. R. VVooLroLK, Jr. 

